Combined indicator and direction controller for synchronous motor-driven clocks



y 50 R. BOYLES 2,513,913

, COMBINED INDICATOR AND DIRECTION CONTROLLER FOR SYNCHRONOUS MOTOR DRIVEN CLOCKS Filed April :50, 1949 x s k .m TN 0 b k n A at mwuww I O Patented July 4, 1950 COMBINED INDICA CONTROLLER TOR AND DIRECTION FOR MOTOR-DRIVEN CLOCK SENCHRONOUS Robert L. Boylcs, Framingham, Mass, assignor to Telechron, Inc., a corporation of Maine Application April 30, 1949, Serial N0. 90,586

2 Claims.

My invention relates to a combined signal and locking device for use on self-starting synchronous clock motors of the type which, if not prevented from doing so, may start in either direction of rotation. The signaling function of the device is to indicate to the user of the clock that the clock has stopped, due to a power failure, and probably requires resetting. When the motor is in normal operation, the combined signal and lock is normally retained in a nonlocking position by magnetic attraction. In case the motor is then de-energized, the device moves by gravity to a locking position. When the motor is again energized, the locking device cooperates with a cam to permit starting only in the desired direction. The device does not move back to the nonlocking position by itself after the motor has started but is oscillated by the motor-driven cam and serves as an oscillating signaling device until moved back to nonlocking position manually.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention reference is made in the following description to the accompanying drawing in which Fig. 1 is a front view of a clock with part of the clock face broken away, the view showing the general relation of my signal and locking device with the motor and clock face signal opening. Fig. 2 is a front perspective view of the combined signal and locking device as removed from the clock. Figs. 3 and 4 are rear views of the motor and device, Fig. 3 showing the device in the nonlocking position, and Fig. 4 in the locking position. Fig. 5 shows the magnetic field circuit of the motor. Fig. 6 shows how the locking cam is driven from the motor, and Fig. 7 is a plan cross-sectional view of the motor showing structural details thereof.

Referring now to the drawing, particularly, Fig. 2, the unitary device here shown is mounted for limited rotation as a unit on a shaft part I which will be pivoted at front and back in the motor frame as indicated in Figs. 5 and 6. At the forward end is a semaphore-like indicator signal part having one portion 2 painted one color, for example, green; and another part 3 painted another color or colors, for example, red and white striped. When in the clock, this multicolored semaphore is behind an opening 4 in the clock face (see Fig. 1), and in different positions of the device either the green or striped portions may appear in such opening. An extension 5 projects to the rear from the outer edge of the signal part 3 and when the green part 2 is in the opening 4, the rear end of extension 5 serves merely as a counterweight. However, when the striped portion 3 of the signal is in the opening 4, the back end of arm 5 rests against a cam 6 driven with the clock by the motor. If the motor is in operation and running in the correct direction, which is the direction indicated by arrows on such cam in Figs. 3 and 4, the cam follower lever 5 rides up and down over the cam lobes and oscillates the semaphore signal and all parts shown in Fig. 2. If, however, the motor attempts to start in the wrong direction, the back end of the arm locks the cam from such backward rotation. In Fig. 4 the arm 5 is shown in position to prevent backward rotation of cam 6. The signal and locking device of Fig. 2 is so balanced and positioned in the clock that it, with its arm 5, moves to locking position by gravity when permitted to do so.

Secured to the rear end of shaft I is a magnetic arm I having a bent over armature end part 8 which, when the green part 2 of the semaphore is in the opening 4, is positioned closely adjacent some magnetic part of the motor field structure such that when the motor is energized and armature 8 is moved to such attracting position with respect to the motor field structure, the armature 8 holds the entire signal device structure of Fig. 2 in a corresponding rotative position against the action of gravity. In Figs. 1 and 3 the signal device is shown as being held in the magnetic attracting position just described, with the cam follower arm 5 removed from the cam and the green portion 2 of the semaphore signal in the clock face opening 4. Fig. 4 shows the position of these parts when the signal device has been turned by gravity to bring cam follower arm 5 against cam 6, armature part 8 away from its attracting position, and the striped part 3 of the signal in opening 4.

The motor which drives the clock has an energizing coil 9 (see Figs. 4 and 5) on a magnetic core I 0 extending between magnetic plates II and I2. The rear plate II has two right angle bends to bring it nearer and parallel to the front plate I2. The rear plate II also has a scalloped opening I3 cut therein to form the circular group of stator pole pieces I4. Secured to. the front plate I2 opposite the stator opening I3 in the rear plate II is a cup-shaped stator pole piece structure I5 made out of magnetic material. The side walls of such cup-shaped part I5 are cut to form tapered pole pieces I6 of the same number as the pole pieces I 4 in the rear plate I I, and the ends of such pole pieces I6 extend between the In Fig. 1, the front plate I2 is broken away with the clock face so that the polar structure I and rear plate H with its pole pieces are shown. It

is noted from Figs. 1, 3, and 5 that the signal armature part 8, when in attracted position, is positioned close to but out of contact with the stator pole piece structure [5. It makes use of the leakage flux between such pole. piece structure i5 and the plate ll of opposite polarity.

The shaft end of armature arm I is separated from plate H by a small air gap. The shaft I of the signal device is of nonmagnetic material. Hence, the armature 1-8 is held in the position of cmagnetic attraction without materially influencing the motor field when the motor is energized. However, this magnetic attraction is not sufficient to pull the armature 8 to attracted position from the position shown in Fig. 4 or from some position intermediate the attracted and fully retracted position, in the range of its oscillation, due to the oscillation of the signal structure by cam 6. The signal structure is so balanced in relation to the available magnetic attracting force when the clock is in a normal upright position that the structure will not move to the attracted position represented in Figs. 1 and 3 by magnetic attraction alone. The signal structure is brought to the attracted position when the motor is energized by hand as by tipping the entire clock clockwise in Fig. l (counterclockwise as viewed from the rear, Fig. 4) until the .signal device will rotate to the attracted position by gravity. Then when the clock is returned to the upright position, the magnetic attracting force is sufficient to retain the signal device in the attracted position of Fig. 1 against gravity. It will be evident that when the entire'clock is tipped counterclockwise as viewed in Fig. 4, the signal device will also be tipped counterclockwise because the lock cam follower arm 5 is resting against cam 6 or some other stop, such as the nonmagnetic part [-8, and cannot rotate further clockwise relative to the clock structure. And since the signal structure is unbalanced, its center of gravity will eventually be carried over and to the left of its aXis by such tipping actionuntil it rotates into the relative position shown in Fig. 3, which is the attracted position. It is prevented from rotating counterclockwise (Fig. 3) beyond such position by a stop which may consist of a tail part ll of the armature arm 1 and the, part 18 spacing the motor stator plates H and I2. I

The rotor of the motor consists of apermanent magnet l9 (Fig. 7) polarized in an axial direction and centered on the motor shaft 20 andmagnetic side plates 2l and 22 having pole pieces 23 rotate only in the direction to drive the :clock i and 24 1 bent toward each other and interleaved to form properly. When blocked from rotation in one direction, it will immediately start in the opposite direction. The motor is geared to drive cam 6 through gears 25 and 26 as shown in Figs. 4 and 6, and the arrow on cam 6, Fig. 4, indicates the correct direction of rotation of the cam when the motor is driving the clock in the correct direction. The drive between the motor and clock hands is not shown but will consist of the conventional, simple, speed reducing gearing. The particular motor 'shown has 30 poles and hence will have a synchronous speed of 240 R. P. M. on cycles. The

cam 6 is geared down to rotate at a fraction of such speed and is shown as having two cam lobes;

hence, the slow speed cam will oscillate the signal at a speed favorable to attracting attention.

I will now review the operation of the apparatus, assuming the clock is in normal operation and the green signal 2 is in the opening 4 with the armature 8 in attracted position as represented in Fig. 1. Assume, now, that the alternating c'urrentexcitation to the motor field coil 9 is cut ofi for some reason, suchas a power failure. Armature parts 'l-8 will no longer be attracted and the entire unitary-indicator and locking pawl structure of Fig. 2 will turn by gravity (counterclockwise in Fig. 1, clockwise in Fig. 3), until the end of arm 5 rests against the now stationary cam 6. This will bring the striped sectorof the semaphore indicator in opening 4 and will indicate to anyone looking at the clock that it has stopped,

since the striped indicator is stationary and not oscillating. Assume, now, that power is resumed. The motor tries to start and does start. If it tries to start in the wrong direction, it is immediately blocked by arm 5 and cam 6. Hence, it starts in the proper direction. The arm 5 acting as a cam follower now rides over the lobes of cam 6 and the red and white striped indicator signal is waved, so as to speak, back and forth in opening 4, indicatingto anyone glancing at the.

clock that it is running, but that it has been stopped at some time previously andprobably needs to be set. The clock is then set to correct time, as needed, in the usual way, and then the signal is returned to green by simply tilting the I clock clockwise .(Fig. 1) until the green signal is seen in opening 4, and then the clock is returned to upright position. tilting operation while the clock is energized brings the armature parts "i-8 to the position where they will be attracted and held by magnetic forces with the cam follower :5 removed from cam 6 and the green signal in opening 4. If desired, the riding of the .cam follower 5 over the cam lobes may also cause an audible signal due to a clicking noise. Such will not be objectionable becauseas soon as the clock is properly set and the signal oriented to green, the audible signal will cease. .Such click g. noise signal will be inherent in the arrangement described but it may be suppressed or made louder by the design, shape, and materia-lof the cam, 01 weight of the cam follower without interfering with other operating features.

What 1 claim as new and desire to secure by Letters Patent of the United States is:

1; In combination with a clock, a self-starting synchronous electric motor for driving said clock, said motor having stationary magnetic stator parts and being of a type capable of starting in either direction of ..rotation, .a :cam driven at slow speed .by said motor,a :unitary device pivoted. for limited rotation, device having a camfollower for cooperating with said cam, a magnetic armature member having attracted and detracted positions with respect to stationary magnetic parts associated with said motor and an indicator for indicating on the face of the clock the rotary position of said unitary device, said unitary device being biased by gravity to an indicating position where its cam follower contacts the cam and its magnetic armature member is in a detracted position range, said cam and cam follower then preventing the rotation of said motor in the wrong direction for driving the clock but permitting its rotation in the correct direction and also serving to oscillate said indicator when the motor is in operation, said magnetic armature member serving, when moved to its attracted position with the motor energized, to hold said cam follower away from the cam and said indicator in a different and stationary indicating position against the action of gravity.

2. In combination with a clock, a self-starting synchronous electric motor for driving said clock, said motor having a stationary magnetic field structure and being of a type capable of starting in either direction of rotation, a cam driven at 10w speed by said motor, a unitary device pivoted for limited rotation, said device having a cam follower for cooperating with said cam, a magnetic armature member having attracted and detracted positions with respect to the stationary magnetic field structure of said motor, and an indicator for indicating on the face of the clock the position of said unitary device, said unitary device being biased by gravity to have its cam follower contact said cam and its magnetic armature member in a detracted position range, said cam and cam follower then preventing the operation of said motor in an incorrect direction for driving the clock but permitting of its operation in the correct direction and also serving to oscillate said indicator when the motor is operating in the correct direction, said magnetic armature serving, when moved to attracted position with the motor energized, to hold said unitary member against the action of gravity in a rotary position where its cam follower is removed from said cam and said indicator is in a different and stationary indicating position.

ROBERT L. BOYLES.

No references cited. 

